title: Differences in muscle activation patterns during step recovery in elderly women with and without a history of falls.
abstract: OBJECTIVE
  This study aimed at comparing the patterns of muscle activation used in stepping to regain balance during a forward fall between subjects with and without a history of falling and at identifying the causes of functional deficits in recovery stepping.
  
  
  METHODS
  Elderly women with and without a history of falling (fallers: n = 12, mean age ± SD = 82.8 ± 4.5 years; non-fallers: n = 17, age = 81.4 ± 3.4 years) participated in the study. The subjects were suspended in a forward-leaning position by a lean-control cable with a load of 15 % of body weight and instructed to regain standing balance upon release by taking a single step forward. Electromyography (EMG) data were obtained from five lower extremity muscles on the stepping side, and the muscle activation patterns were compared between fallers and non-fallers.
  
  
  RESULTS
  Fallers had a shorter step length and slower step velocity than non-fallers. The EMG time-to-peak for the gastrocnemius muscle, which provides push-off prior to foot lift-off, was slower for fallers than for non-fallers, whereas the EMG onset times of the biceps femoris and gastrocnemius muscles were similar between the groups. The fallers exhibited significantly delayed muscle deactivation of the upper leg and increased co-contraction between the rectus femoris and biceps femoris during the stepping phase than did the non-fallers.
  
  
  CONCLUSIONS
  These findings suggest that the muscle activation pattern during the regain balance may reflect an inability to step forward rapidly in elderly women with a history of falls.
authors.affiliation: Division of Physical Therapy, Faculty of Care and Rehabilitation, Seijoh University, 2-172 Fukinodai, Toukai, Aichi, 476-8588, Japan, ochi@seijoh-u.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Ochi
authors.forename: Shinya
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Abe
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Tateuchi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ichihashi
mesh_terms: D000058:Accidental Falls; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D007866:Leg; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D004856:Postural Balance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D016138:Walking / Q000502:physiology